A computer can operate in a normal mode and a sleep mode such as a power saving mode. When the computer has not been used for a period of time, the computer automatically goes to sleep or the computer may be manually set into a mode such as the sleep mode by a user. Status indicators are usually used to display different operational states of the computer, and the display of the status indicators varies with the operational status of the computer. For example, two status indicators are disposed on a mainboard or a display of the computer. When the computer operates in the normal mode, one of the status indicators is continually lit, and another status indicator goes off. Conversely, when the computer operates in the sleep mode, the one status indicator goes off, and the another status indicator is continually lit. However, an interface card for controlling the conventional status indicator only has a single support interface, and specific types of transmission interfaces cannot be selected according to different requirements, which result in incompatibility in communication interfaces between a mainboard and the interface card.